题目

如图为一自行车的手闸，手捏处做的比较粗糙是为了________．手闸形状被设计成扁扁的方形是为了________．当需要刹车捏闸时，它是一个________（选填“省力”或“费力”）杠杆． 答案：增大摩擦   减小压强   省力  _______, I am determined not to play computer games and ______myself in doing something meaningful.   A. From now on; employ   B. From now on; bury     C. Since now on; devote    D. From today on; explore